Influence of Aging on Surface Free Energy of Asphalt Binder

Surface free energy of asphalt binder is related to the work of cohesion within the binder and the work of adhesion between binder and aggregate. The sessile drop method was used in this study to measure the contact angle between asphalt binders and three probe liquids. From these measurements, the surface free energies of the asphalt binder were determined using the Owens-Wendt method. The rolling thin film oven test (RTFOT) and pressure aging vessel (PAV) test were carried out to age asphalt binders, through which the influence of aging on the surface free energy was investigated. Results indicated that both RTFOT and PAV aging processes can reduce the surface free energy for most asphalt binders, which means the asphalt binder has the tendency to crack due to RTFOT and PAV aging.